Introduction to
Neuropsychology
Clinical Neuroscience
Emerging field – application of neuroscience
to mental health
In this course you will become more familiar
with neuroanatomy, neurochemistry, and
neurophysiology.
Our goal is translating this information so that
it will have practical applications to your
practice as a therapist.
Neuropsychology
Subfield of the neurosciences
Study of the relation between human brain
function and behavior
Draws from many disciplines
Professional organizations
APA Division 40, Clinical Neuropsychology
http://www.div40.org/
National Academy of Neuropsychology (NAN)
http://nanonline.org/
The International Neuropsychological Society (INS)
http://www.the-ins.org/
1
Definition of Clinical Neuropsychologist
A professional psychologist who applies principles of assessment
and intervention based upon the scientific study of human
behavior as it relates to normal and abnormal functioning of the
central nervous system.
A doctoral-level psychology provider who has demonstrated
competence in the application of such principles for human
welfare following:
A. Successful completion of systematic didactic and experiential
training in neuropsychology and neuroscience at a regionally
accredited university;
B. Two or more years of appropriate supervised training
applying neuropsychological services in a clinical setting.
C. Licensing and certification to provide psychological services
to the public by laws or the state or province in which he or she
practices;
D. Review by one's peers as a test of these competencies.
Historical View of Neuropsychology
Neuropsychology is strongly influenced by 2
traditional foci of experimental and theoretical
investigations:
1.
2.
The brain hypothesis: the brain is the source of
behavior
The neuron hypothesis: the unit of brain structure
and function is the neuron
The Brain versus the Heart
Alcamaeon of Croton – located mental
processes in the brain (the brain hypothesis)
Empedocles of Acragas – located mental
processes in the heart (the cardiac
hypothesis)
The relative merits of these two hypotheses
were debated from the next 2000 years.
2
Descsartes: The Mind-Body Problem
Introduced idea of a singular soul – called the
mind
Described the mind as non-material and
separate from the body (dualism)
Proposed body is like a machine (responding
mechanically and reflexively to influences),
but the mind decides what movements the
machine makes.
Beginning of the mind-body problem: How
can a nonmaterial mind produce movements
in a material body?
Descartes: The Mind-Body Problem
Laws of physics at the root of the problem
For the mind to affect the body it would have to
expend energy – thus adding new energy to the
material world
The creation of new energy violates a
fundamental law of physics.
Thus dualists, have a problem explaining how the
mind (immaterial) and the body (material) interact.
Monists – avoid the problem by stating the
mind and body are two words for the same
thing (includes most neuropsychologists)
Darwin and Materialism
By mid-19th century- emergence of
materialism, the idea that rational behavior
can be fully explained by the workings of the
nervous system.
Rooted in work of Darwin & Wallaceevolutionary theory that all living things are
related.
All living things have a common ancestor:
brains of all animals are related.
Leads to belief that human behavior is also a
product of the brain.
3
Localization of Brain Function
Thomas Willis (1621 – 1675)
Medical physiologists – used clinical observations
and scientific methods to study the nervous
system
Used dissection to learn functions of some of
brain structures
Localization of Brain Function
Gall and Phrenology
First general theory to present the idea that
different parts of the brain had different functions
Did make a number of important discoveries in
neuroanatomy
Theory of brain function called localization of
function
Related individual differences to prominent features of
head and skull
Bump = well-developed cortical gyrus and greater ability
Depression = underdeveloped gyrus and reduced ability
4
Recovery of Function: Pierre Flourens
Pierre Flourens (1794-1867): Developed
method of controlled laboratory experiments
Removed parts of animal brain to study changes
produced in their behavior and how they
recovered from the loss of brain tissue.
He varied the location from which he removed
tissue in order to search for different functions.
Saw that animals eventually recovered to the
point where they seemed normal
Led him to refute idea that different areas of the
cortex had specialized functions – argued cortex
worked as a whole
Localization of Language
Discovery that launched the science of
neuropsychology!
Began with Jean Baptiste Bouillaud and his sonin-law, Ernest Auburtin: as early as 1825 argued
that speech controlled by left hemisphere
Auburtin in 1861 presented patient who lost
ability to speak due to pressure on frontal lobe
Promised: to examine autopsy and “renounce” his
ideas if the frontal lobes were not compromised
Paul Broca invited Auburtin to examine his
patient, Monsieur Leborgne, who’s brain at
autopsy revealed lesion in region now known as
Broca’s area.
5
Sequential Programming
Strict localizationists argued:
A behavior is controlled by a specific brain area
Destroying the area selectively destroys the
behavior
Wernicke was 1st notable scientist to dissent
– he saw aphasic patients that differed from
Broca’s
Damage in first temporal gyrus
No contralateral paralysis
Patients spoke, but made no sense
Could hear, but no understand or repeat what was
said to them
Sequential Programming and Disconnection
Wernicke found that the temporal lobe is also
involved in language.
Disproved the strict localizationists view that
language was localized only to part of the
frontal lobe.
He also provided the 1st model for how
language is organized in the left hemisphere.
6
Disconnection
Idea of disconnection: although different
regions have different functions, they are
interdependent – to work they must
communicate.
Important idea – predicts that complex
behaviors are built up – assembly-line
fashion – as information collected by sensory
systems enters the brain and travels through
different structures before resulting in an
overt response.
Electrophysical Confirmation of
Localization
New technique to study the brain – placing a think
insulated wire, an electrode, onto or into the cortex,
and passing a small electrical current through the
uninsulated tip of the wire, thus exciting the tissue
near the electrode tip.
Fritsch & Hitzing – showed that stimulating the
cortex produced movement
Stimulation of parts of frontal lobe elicited movement of
particular body parts – suggest the cortex possess
topographic representations of different parts of the body
7
Hierarchical Organization of the Brain
Fritsch & Hitzig concluded that that the
cortical area involved was necessary and
sufficient for producing the movement.
Goltz in 1892 tested this idea: he argued that
if the neocortex has a function, then removal
of the cortex should lead to a loss of that
function.
Removal of cortex did not appear to
completely eliminate any function, though it
reduced all functions to some extent.
Hierarchical Organization of the Brain
This contradiction was resolved by
hierarchical organization concept of brain
function (John Hughlings-Jackson -18351911).
Nervous system is organized in a functional
hierarchy with each successively higher level
controlling more complex aspects of
behavior, but doing so through the lower
levels.
Hierarchical Organization of the Brain
He suggested that diseases or damage that
affect the highest levels would produce
dissolution (opposite of evolution): the
animals would still have the repertoire of
behavior but at a simpler level (like animals
who have not evolved the missing brain
structure).
We now recognize that that functions are
localized in one sense but are also distributed
over wide areas of the brain in another
sense.
8
The Neuron Hypothesis
The nervous system is
composed of discrete,
autonomous units or
neurons, than can
interact but are not
physically connected.
Next, we will discuss
how the neuron
hypothesis led to a
number of ideas that
are central to
neuropsychology.
The Neuron
Earliest anatomists found the substructure of
the nervous system to resemble a goo
(gelatinous white substance).
Able to see more when learned to dehydrate
brain tissue and view thin slices
Use of microscope in 1700 – 1800s helped
increase understanding
Biggest advance was staining – stains
applied to tissue slices allowed different
structures to be distinguished
Golgi and Neural Histology
Italian anatomist, Camillo Golgi, in 1875,
injected tissue with silver nitrate
A few entire cells became encrusted with
silver – allowing entire neuron to be
visualized for the first time
Could see it was a very intricate system
Which lead to the next debate …. How did
the nervous system work? Was it a net of
physically connected fibers or a collection of
separate units?
9
Golgi vs. Cajal
Golgi argued that axons were interconnected
forming an axonic net
Cajal argued the cells were separate – in his
examinations he never saw connections from cell to
cell.
Further History
We’ve established foundations for the brain
hypothesis and the neuron hypothesis; two ideas
that have strongly influenced neuropsychology.
See text for discovery of the synapse, realization of
chemical communication between cells, and
understanding of the action potential.
Also interesting is the history of neurological
approaches to mental illness.
See NPR story on transorbital lobotomy
http://www.npr.org/templates/story/story.php?storyId=5014
080
10